Sm---Nd age and REE geochemistry of Proterozoic arc-related igneous rocks in the Richtersveld subprovince, Namaqua Mobile Belt, Southern Africa

Igneous rocks of the Richtersveld Subprovince in South Africa and Namibia form a Palaeo-Mesoproterozoic arc complex, dominated by extrusive andesites and their plutonic equivalents (diorites, tonalites), although the whole spectrum of rock types from ultramafic to felsic is present. Sm---Nd isotope data indicate an extrusion age of 2000 Ma, thereby confirming previously published Rb---Sr and U---Th---Pb ages. Initial Nd, Sr and Pb isotope ratios indicate a juvenile crust-producing episode at this time, with rapid recycling of young crust to generate rhyolitic and granitic components within the arc complex. The Richtersveld Subprovince represents the oldest crust in the western Namaqua Province, which was subsequently recycled during post 2.0 Ga tectonothermal events, especially the 1200–1000 Ma Kibaran episode.